1. Field of the Invention
The present invention relates to an image projector for microfilm reader-printers, and electrophotographic copying machines and the like.
2. Description of the Related Art
The aforesaid type of image projector has a density detector for photoreception of the projection image of an original document for detecting the image density of the document at the photoreception portion. Adjustment of the light intensity of the light source, discrimination of positive or negative original document, and control of other image forming conditions is accomplished in accordance with the density variation and distribution of the detected image density.
The detection of the image density is preferably accomplished over as broad a region as possible for the original document image, and a variety of arrangements have been tried to prevent an inclination of a portion of the image or the vertical and horizontal lines. For example, one method provides a multiple arrangement of a plurality of photoreception portions in a range corresponding to the projection image, while another method moves a photoreceptor portion over the projection image by means of a moving mechanism unique to the photoreceptor portion and provided with a cam, as described in Japanese Laid-Open Patent Application No. 60-45436.
However, arrangements providing multiple photoreception portions, and having a unique moving mechanism with a cam, such as the arrangement described in Japanese Laid-Open Patent Application No. 60-45436, are complex in construction, increase the overall size of the apparatus, and thereby present certain disadvantages with respect to control and labor.